The invention relates to self-cleaning rotating mirrors.
Rotating mirrors have become key optical components in a variety of imaging systems such as photographic mechanical cameras and photolithography equipment. Typically, the rotation of the mirror redirects a laser from a fixed light source onto an imaging plate, allowing the laser to traverse the lateral dimension of the imaging plate in each rotation sequence. At the same time, however, the rotating mirror sweeps the air around it making it susceptible to particle deposition on the mirror. Particles on the mirror will have adverse effects on the quality of the redirected light causing a loss of quality in the resulting image.
The invention is based on the discovery that by creating an air flow using a filter compressor assembly directly linked with a rotating mirror and directing the resulting air flow, e.g., with a shroud, a continuous flow of clean air is passed over the surface of the mirror, preventing the deposition of particles onto the mirror surface.
In one aspect, the invention features a self-cleaning mirror including a cylindrical shaft having a mirror face at one end thereof and a longitudinal axis, and a compressor assembly arranged on the cylindrical shaft near the mirror face, such that rotation of the shaft causes air to be compressed by the compressor assembly and flowed around the mirror face.
Embodiments of this aspect of the invention can include one or more of the following. The compressor assembly can include a filter. The compressor assembly can be a centrifugal compressor, an axial flow compressor, a radial flow compressor, or a mixed flow compressor.
The compressor assembly also can be a filter impeller compressor which includes an impeller disk and a plurality of blades made from a filter material. The filter impeller compressor can have an axial flow configuration, a centrifugal flow configuration, or a radial flow configuration.
In another aspect, the invention features a self-cleaning mirror includes a cylindrical shaft having a mirror face; and a compressor assembly having an impeller disk, a plurality of blades, and a filter. The impeller disk, the plurality of blades, and the filter are fixed about the circumference of the cylindrical shaft.
Embodiments of this aspect of the invention can include one or more of the following. The compressor assembly can further include a shroud attached to the plurality of blades. The compressor assembly can be a centrifugal compressor, an axial flow compressor, a radial flow compressor, or a mixed flow compressor. The self-cleaning mirror can further include a motor having a drive mechanism and a housing, wherein a first end of the cylindrical shaft is connected to the drive mechanism. The compressor assembly can further include a shroud attached to the motor housing. The compressor assembly can further include a shroud resting on a slip mechanism fixed to the cylindrical shaft. The compressor can further include a shroud fixed to the plurality of blades. The shroud can be fixed to the impeller ring.
In another aspect, the invention features a self-cleaning mirror including a cylindrical shaft having a mirror face; and a compressor assembly having a filter impeller. The compressor assembly is attached about the circumference of the cylindrical shaft near the mirror face.
In another aspect, the invention features a method of improving rotating mirror performance by inhibiting particle deposition. The method includes the steps of providing a mirror assembly including a shaft having a mirror face at one end thereof; attaching a compressor assembly to the shaft near the mirror face; and rotating the mirror assembly and compressor assembly to cause compressed and filtered air to flow over the mirror thereby improving rotating mirror performance.
The invention provides several advantages. For instance, the self-cleaning action of the rotating mirror reduces the deposition of particles in the surrounding air onto the mirror surface resulting in less-frequent cleaning of the optical system and better clarity when using the rotating mirror assembly to create optical images. Additionally, the self-cleaning action can allow the mirror to be rotated at faster rates thereby producing a better resolution at a shorter time interval of image production without substantially increasing the rate of particle deposition on the mirror surface.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.